diff --git a/src/iomux_select.c b/src/iomux_select.c
index fb1517a..bdf0029 100644
--- a/src/iomux_select.c
+++ b/src/iomux_select.c
@@ -27,15 +27,14 @@ static int iomux_select_update_events(struct IOMux *mux_, struct IOMuxFD *fd);
 static void iomux_select_recalc_max(struct IOMuxSelect *mux)
 {
     size_t i;
+    size_t n;
     mux->max_fd = -1;
 
-    for (i = 0; i < mux->num_descriptors; ) {
+    for (i = 0, n = 0; i < FD_SETSIZE && n < mux->num_descriptors; i++) {
         if (mux->descriptors[i] != NULL) {
             mux->max_fd = UC_MAX(mux->descriptors[i]->fd, mux->max_fd);
-            i++;
+            n++;
         }
-
-        assert(i < FD_SETSIZE);
     }
 }